90 PHYSIOLOGY AT THE FARM. 



Pharynx and Gullet. The pharynx and gullet remain for 

 notice, in order to complete the account of the parts concerned 

 in deglutition. The pharynx is the expanded upper part 

 of the alimentary canal, communicating, on the one hand, 

 with the cavity of the mouth; on the other, with the canal 

 formed by the gullet. It has a conical form, the smaller 

 end being directed downwards. In the second stage of deglu- 

 tition the masticated food passes into the pharynx over the 

 epiglottis, which guards the orifice of the larynx. By the con- 

 traction of the pharynx it is transmitted into the gullet. 

 The gullet, termed also the oasophagus, is a very muscular 

 tube, being indeed the most powerfully muscular part of the 

 whole length of the primes vice. The muscular fibres differ 

 in the ox from those in the human gullet, by decussating 

 each other, and running spirally in opposite directions : these 

 muscular fibres, at the same time, are remarkably strong. The 

 lining mucous membrane of the gullet is plentifully supplied 

 with secreting follicles for the lubrication of the tube. The 

 gullet tapers as it slopes backwards, and, passing between 

 the two sacs of the pleura in the chest that is, through the 

 mediastinum it proceeds, between the pillars of the dia- 

 phragm, to terminate in the paunch or first stomach. 



Arteries. The arteries which supply blood to the several 

 parts of the mouth and the pharynx are branches of the ex- 

 ternal carotid, while the gullet receives blood from the posterior 

 aorta. The distribution of these arteries is so similar to what 

 was before stated respecting the corresponding blood-vessels in 

 the horse, that it seems superfluous to repeat the description. The 

 same observation applies to the veins and nerves (pp. 25, 26). 



Deglutition. The changes which take place on the food in 

 the mouth of the ox are chiefly effected after it has been swal- 

 lowed, and has remained for some time in the paunch or first 

 stomach, and in the honeycomb or second stomach, and is 



